1. Technical Field
The present invention relates to the manufacturing of optical subassemblies and modules.
2. Description of the Related Art
For the manufacturing of optical subassemblies and modules, which comprise standard VCSELs (vertical cavity surface emitting laser) and Photodiodes, one of the main challenges is the very precise alignment of these devices with respect to the light carrying medium (i.e. fibres or waveguides). For optical multi-mode applications, that is. where multiple optical modes propagate through the fibres/waveguides, potentially at different speeds, leading to pulse-distortion at higher data-rates, mechanical alignment accuracies in the order of 5 μm (micrometers) are required.
Many concepts have been proposed in the past, e.g. using passive alignment with different types of packages or optical subassemblies. Very few of them ever made it into a product, mostly because of large scale manufacturing problems and high cost. Independent of the concept used is the fact that no matter what, at one moment in time the electro-optical components must be aligned with the required accuracy with respect to either a package, board or a subassembly.
With the constant increase of data-rates and “bandwidth”, new generations of systems are carefully considering the need to migrate to optical transmission to meet product performance targets. So far the limiting factor has been the cost of producing affordable optical transceiver assemblies which convert electrical signals into optical pulses and on the other end of the signal path to reconvert optical inputs back into electrical signals. Integration of rigid structures or even the uses of fibre bundles are complex and cumbersome to the overall system architecture.
U.S. Pat. No. 7,336,864 describes an opto-electronic board including a printed wiring board with an optical waveguide, a metallic area, and a hole, wherein an abutting face of the optical waveguide and an abutting face of the metallic area form a part of the side face of the hole. The opto-electronic board further comprises an opto-electronic circuit with a bonding pad, wherein the opto-electronic circuit is arranged in the hole and soldered with its bonding pad to the abutting face of the metallic area.